1. Field of the Invention
This invention relates to coin telephone control circuits and, in particular, to a coin control circuit for use with subscriber loop carrier systems.
2. Description of the Prior Art
Normally a .+-.130 volt pulse with a width of about 750 milliseconds is transmitted from a central office to operate a coin telephone relay for collecting or returning coins, respectively. This pulse cannot be transmitted over a subscriber loop carrier system. Consequently, Mr. J. W. Schrage, in his application, Ser. No. 234,250, filed concurrently herewith and assigned to the same assignee, has suggested a solution. A plurality of capacitors are charged in parallel from the telephone line or from a low power voltage source at the remote carrier terminal. As and when coins are to be collected or returned, one of the capacitors is discharged to provide the coin control pulse. Whereas this solution permits the generation of a coin collect or refund pulse, an uneconomical use of remote carrier terminal power results. In a subscriber loop carrier system powered entirely from the central office, it is desirable to conserve such remotely consumed power.